The present invention relates to a method of folding an air-bag, and more particularly relates to a method of folding an air-bag for use in a motor vehicle.
It has been proposed to provide an air-bag in a motor vehicle adapted to be inflated in the event that an accident should occur. The air-bag, when inflated, is located in front of an occupant of the vehicle in order to protect the occupant of the vehicle.
It is necessary to inflate the air-bag extremely swiftly once an accident situation occurs. In many prior proposed air-bags, as a consequence of this rapid inflation, the fabric forming the air-bag is given a very high acceleration, and the fabric can impinge upon the occupant of the vehicle, injuring the occupant of the vehicle.
It has been proposed to fold an air-bag by providing the air-bag with linear folds in one direction, in a concertina-fashion, and subsequently providing the bags with linear folds in a perpendicular direction. This can cause a very high internal pressure which can give part of the fabric of the bag a very high initial acceleration.
It has also been proposed to provide an air-bag with concentric circular folds, as in GBA-2,279.046. Such an arrangement may provide very easy unfolding of the bag, but nevertheless, the inflation characteristic is still less than totally desirable.
U.S. Pat. No. 5,425,551 discloses an arrangement in which an air-bag initially has peripheral side portions rolled or folded inwardly, to form two parallel rolls, and subsequently is rolled perpendicularly to the initial rolls or folds to provide two further inwardly directed rolls. The two further inwardly directed rolls may be positioned in front of the rest of the air-bag. Part of the air-bag adjacent the gas generator is untensioned in one direction, but is tensioned in the other direction. The rolled portions of the bag have to be ejected from the housing as the first stage in the inflation process.